Double-layer structure combined with FSS design for the improvement of microwave absorption of BaTiO₃ particles and graphene nanoplatelets filled epoxy coating

Graphene nanoplatelets (GNPs) and BaTiO₃ particles filled epoxy coating with wide microwave absorption bandwidth were designed and investigated in the frequency range of 2–18 GHz. The microstructures of these coatings exhibit a uniform dispersion of GNs and BaTiO₃ particles in the matrix. The double-layer structure and frequency selective surfaces (FSS) design were used to improve their microwave absorption of such coatings. A bandwidth of reflection loss (RL) ≤ −8 dB with 13.9 GHz (from 4.1 to 18 GHz) can be obtained for the double-layer coating combination of FSS structure. The microwave absorption of such double-layer absorber with FSS structure also depended on the incidence angles and polarization model, and higher RL performance is maintained under wide oblique incidence for both TE and TM polarization.